CVE-2026-54133: Mtdowling/jmespath.php Jmespath.php Has CompilerRuntime Code Injection Vulnerability
CRITICALCVE-2026-54133 is a CRITICAL (CVSS 9.8) jmespath.php has compilerruntime code injection vulnerability (CWE-116: Improper Encoding or Escaping of Output) affecting Mtdowling/jmespath.php libraries in the Packagist ecosystem. The issue involves jmespath.php has compilerruntime code injection via unescaped function names. Remediation is available by upgrading affected packages to version 2.9.1.
CVE-2026-54133 at a Glance
Security Impact
CVSS: 9.8
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
How to Fix CVE-2026-54133
To remediate this vulnerability, upgrade all affected Mtdowling/jmespath.php dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade mtdowling/jmespath.php to 2.9.1
Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for mtdowling/jmespath.php
How to Check if You Are Affected
To determine whether your application is affected by CVE-2026-54133, inspect your project dependencies for Mtdowling/jmespath.php:
inspect dependencies for mtdowling/jmespath.php
Analyze the terminal output to locate any version of Mtdowling/jmespath.php in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.9.1), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-116: Improper Encoding or Escaping of Output, where the product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. as a result, the intended structure of the message is not preserved. In Mtdowling/jmespath.php, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-54133 Affected Mtdowling/jmespath.php Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
mtdowling/jmespath.php
|
Packagist |
< 2.9.1
|
2.9.1
|
References
Frequently Asked Questions
What is CVE-2026-54133?
Which Mtdowling/jmespath.php versions are affected?
What version fixes CVE-2026-54133?
Is mtdowling/jmespath.php affected?
What is the CVSS score of CVE-2026-54133?
What CWE is associated with CVE-2026-54133?
How can I check Packagist dependencies for CVE-2026-54133?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-pcw8-m77r-2528",
"modified" : "2026-08-18T20:16:38Z",
"published" : "2026-08-18T20:16:38Z",
"aliases" : [ "CVE-2026-54133" ],
"summary" : "jmespath.php has CompilerRuntime code injection via unescaped function names",
"details" : "## Impact\n\n`mtdowling/jmespath.php` can generate and execute attacker-controlled PHP code when `JmesPath\\CompilerRuntime` is used with an attacker-controlled JMESPath expression. The compiler emits parsed JMESPath function names into generated PHP source without sufficient escaping. A crafted expression can cause the generated cache file to contain executable attacker-controlled PHP, which is then loaded by the compiler runtime.\n\nA vulnerable flow is:\n\n1. An application accepts or constructs a JMESPath expression using attacker-controlled input.\n2. The expression is evaluated with `JmesPath\\CompilerRuntime`, or with `JmesPath\\search()` while `JP_PHP_COMPILE` is enabled.\n3. The crafted expression uses a non-identifier value where the parser accepts a function callee.\n4. The compiler writes that value into generated PHP source without safely escaping it as a PHP string literal.\n5. The generated source is written to the compiled-expression cache directory.\n6. `CompilerRuntime` loads the generated cache file.\n7. The injected PHP executes in the context of the affected application.\n\nIn that flow, an attacker can execute arbitrary PHP code with the privileges of the PHP process. The searched data document is not sufficient to exploit this issue by itself; the attacker must be able to influence the JMESPath expression string.\n\nThe default runtime used by `JmesPath\\search()` is `AstRuntime`, which interprets the parsed expression tree and is not affected unless `JP_PHP_COMPILE` is enabled. Applications are most likely to be affected when they explicitly instantiate `JmesPath\\CompilerRuntime`, enable `JP_PHP_COMPILE` as a performance optimization, and allow users to provide JMESPath expressions for filtering, querying, or transforming data.\n\n## Patches\n\nThe issue is patched in `2.9.1` and later.\n\n## Workarounds\n\nIf you cannot upgrade immediately, disable `JP_PHP_COMPILE` and do not use `JmesPath\\CompilerRuntime` with attacker-controlled expressions. Use the default `AstRuntime` for untrusted expressions. Applications that must continue accepting untrusted JMESPath expressions before upgrading should ensure those expressions are never evaluated by the compiler runtime.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Packagist",
"name" : "mtdowling/jmespath.php"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.9.1"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/jmespath/jmespath.php/security/advisories/GHSA-pcw8-m77r-2528"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-54133"
}, {
"type" : "WEB",
"url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/mtdowling/jmespath.php/CVE-2026-54133.yaml"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/jmespath/jmespath.php"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-116", "CWE-20", "CWE-94" ],
"severity" : "CRITICAL",
"github_reviewed" : true,
"github_reviewed_at" : "2026-08-18T20:16:38Z",
"nvd_published_at" : "2026-06-12T15:16:31Z"
}
}